Catalytic oxidation processes are important routes to many commercial chemicals. For example, numerous commercial processes for the epoxidation of olefins have been disclosed in the art. One such process involves the reaction of an organic hydroperoxide with an olefin in the presence of catalytic amounts of certain soluble transition metal compounds (e.g., molybdenum, tungsten, or vanadium napthenates). Some drawbacks to this process include co-production of an alcohol from the hydroperoxide, recovery of the soluble metal catalyst, and the sensitivity of the reaction to water.
Heterogeneous catalysts which overcome some of the aforesaid problems have also been developed. U.S. Pat. No. 3,923,843 claims a process for the epoxidation of an olefinically unsaturated compound comprising reacting the compound in the liquid phase with an organic hydroperoxide in the presence of a catalyst comprising an inorganic siliceous compound in chemical combination with an oxide or hydroxide of titanium. The catalyst is treated with an organic silylating agent before use. In the examples shown, the epoxide selectivity is increased from about 3% to about 15% when comparing the untreated catalyst to the silylated form.
Hydrogen peroxide is often employed as an oxidizing agent for the production of organic chemicals. A wide variety of organic compounds may be oxidized utilizing hydrogen peroxide, for example, olefins can be oxidized to epoxides (oxiranes) using this reagent.
Many titanosilicates have been reported to be useful as oxidation catalysts. For example, the catalytic oxidation of alkanes and alkenes by titanium silicates is disclosed in C. B. Khouw et al., "Studies on the Catalytic Oxidation of Alkanes and Alkenes by Titanium Silicates", Journal of Catalysis 149, 195-205 (1994). Such catalysts are used for the selective oxidation of n-octane using organic hydroperoxides as the oxidants at temperatures below 100.degree. C. The absence of water is deemed critical for catalytic activity.
In this regard, there is a need for processes that can utilize aqueous hydrogen peroxide rather than organic hydroperoxides to provide both a safe and an efficient process for oxidizing organic compounds. The present invention satisfies that need, but yet can still be used with organic hydroperoxides, and also overcomes certain deficiencies inherent in the prior art. Other objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description which follows hereinafter.